Transfer molding is widely used as a method of packaging semiconductor devices, such as ICs (integrated circuits) and LSI chips, with epoxy resin compositions to obtain semiconductor devices due to its advantages of low cost and suitability for mass production. In transfer molding, modification of epoxy resins or phenol resins as curing agents can lead to improvements in the characteristics and reliability of semiconductor devices.
Such epoxy resin compositions include an epoxy resin, a curing agent, a curing catalyst, and the like. As the curing catalyst, imidazole catalysts, amine catalysts, and phosphine catalysts have usually been utilized.
With the trend toward compact, lightweight and high-performance electronic devices, high integration of semiconductor devices has been accelerated year by year. Problems unsolved by conventional epoxy resin compositions arise with increasing demand for surface mounting of semiconductor devices. Other requirements for packaging materials for semiconductor devices are rapid curability to improve productivity and storage stability to improve handling performance during distribution and storage.
Korean Patent Publication No. 10-2014-0082528A discloses an epoxy resin curing catalyst using tetravalent phosphonium salts.